We both knew this letter has been a long time coming. Or at least I did, starting around the time The Riddler kidnapped those ichthyologists from Gotham University and forced them to custom-breed hammerhead sharks with question-mark-shaped heads. The nightwatchman at that deepwater crossword puzzle factory owes you his life.

But here's the thing — you never left that deepwater crossword puzzle factory. Mentally, I mean. Once the flashbulbs died down and the ink dried on Vicki Vale's evening edition write-up for the Gotham Gazette, your thoughts remained forever out at sea.

And when we made love that night, you were silently preoccupied with the outside possibility that somewhere, somehow Two-Face was grafting 50% of a megamouth on to 50% of a cookiecutter. (How do I know this? We never agreed on "megacookie" as a safeword.)

So yes, no more sleeping alone. No more gin-fueled shouting matches during Shark Week. No more blaming your "caped employer." I'm leaving the widow's walk. I'm leaving you.

Things weren't always like this. When we first met years ago, you seemed so effervescent, so fizzy, almost bursting at the seams with vitality. I had no clue at the time that you were simply riding the highs of early career victories.

Eventually a pinch of you was all your employer needed. You were so effective, so exacting, all precise tool, no blunt object. When the public understood this, and their adulation metamorphosed into tacit acceptance.

You had respect and reputation, and you had me. You hit your stride, and then it all collapsed.

In those heady days, you'd expectorate wild ideas about your own career advancement. Becoming a permanent fixture of Gotham Central or Arkham? No spitballing session was too starry-eyed. But when the phone stopped ringing, you took that as a sign of your own failings. You couldn't understand that times were changing. The business had evolved. Back then, it was great whites stoned to the gills on Smilex gas. Now it was out-of-control Ecstasy dealers.

Your job became a duty. Your duty became a vigil. Do you know how many dinners I ate alone because of a creeping suspicion that somebody filled Jim Gordon's condo with makos? You missed our anniversary twice because you wagered that "Mr. Freeze is out there, weaponizing hákarl." And when Poison Ivy genetically engineered that species of carnivorous sargassum, the forensic reports left you so crestfallen I didn't hear from you for three days.

Remember when we tried to see that therapist? You couldn't go because you of a hunch Scarecrow might try to terrorize "a haunted hayride — a haunted hayride on gondolas." When I asked if that was even a thing, you harangued me about "ignoring the danger to the innocent children, the danger that is thresher sharks whose tails have been replaced with farming scythes." This conversation happened in late July.

Even your boss began to notice your flightiness. You once spent an entire week shadowing Mr. Polka-Dot because an anonymous tipster in the Crime Alley Tattler supposedly saw him snooping around the Gotham Sturgeon Festival. GCPD immediately confirmed it was Crazy Quilt panhandling for loose cigarettes, but you were too stubborn. Like Jimmy McNulty, you needed one more fix of glory.

Consider this — you know how your boss always pointedly invites you to Justice League confabs? Aquaman attends those meetings. And why did the Justice League hire Aquaman? To telepathically persuade sharks into not attacking the only non-superpowered person in the clubhouse. You see where I'm going with this?

Look, I don't want to hurt you. I don't want to dredge up the past. I just need to go, far from insecure, frenzied pillow talk about the subpar morphology of barracudas and whether or not Kite Man could teach a basking shark to parafoil. I'm woebegone, and you're obsessed with wobbegongs.

You once said that you'd do anything for me, even sort of confuse Calendar Man's Arbor Day Megalodon for a few minutes. If that is truly the case, let me go. Just let me go. These Bat-times are not the same, and the Bat-channel has turned the final time.